C43 Has Lost Some Acceleration-Slugish?

[speedybenz]

I have a 1999, C43 that seems to be somewhat slugish. This condition just sort of evolved over the last few weeks.

Motor is stock except for new NGK plugs and Magnecor Spark Plug wires. K&N air filters 1000 miles ago. No engine check light.

I did install a dual exhaust a few weeks ago. Its a 2.5"diameter piping with a big Magnaflow muffler. Removed the resonator and stock AMG muffler. I don't think this is the problem, but maybe.

Car has 69,000 miles. What about O2 sensor, cats, etc. MAF still good, or at least there is no engine check light as stated above.

Tailpipes are black at the bottom of the tips. Car does not burn oil.

Any ideas?

Jeff

[manny]

It is very common to lose torque ( sometimes a considerable amount ), when you go to a large diameter exhaust system.
Most production engines are designed to work with a certain amount of back pressure, which is drastically reduced, or eliminated, by the substitution of mufflers / pipes.
P.S. I will gladly trade you the " sluggish " acceleration of your C 43, for my C 230.

[blackmercedes]

I agree. I doubt the AMG 4.3L V-8 was suffering from excessive backpressure. The AMG exhaust system was carefully engineered to work with the engine and intake system. Things like the camshaft profiles, timing and intake runner design were all carefully chosen to work together. Do you really think they left a bunch of HP on the table? Not likely.

Your aftermarket exhaust has probably resulted in a drop in midrange power, and possibly peak power as well.

[speedybenz]

Do I think Mercedes left a bunch of Hp on the Table? Hell yes I do.

All you have to do is look at the specific output of the current BMW M3 or S2000 Honda, which did sacrifice some low rpm power for top end, but also has a 120Hp per liter output. I could live with a little bit less low end for performance like that.

Lets be real, these newer 3 valve motors are not works of engineering greatness with regard to Hp. There prime emphisis was good emissions and respectable Hp.

100Hp per liter is not leaving Hp on the table. 70Hp per liter is not really earth shattering Hp for the C43. So there is lots of room for improvement.

In addition the car ran very hard with the new exhaust. The loss in response started a couple of weeks after the install.

Jeff

[Tump]

Dear Jeff:

I was thinking of subsituting a set of straight custom x-pipes for the center resonator leading to the stock AMG muffler on my 1999 C43 AMG.

The reason for this mod. is I ran over a large rock that fell from a landscaper's truck after I lowered my car -- bummer -- and it put a large dent in the center resonator. The car still sounds and runs fine but, I think the power would be off some.

Do you have any updates about your expericence with deleting the center resonator? Did the car gain power before you experienced the torque loss? Have you found the culprit?

If you could, would you post specific details (measurements, etc.) regarding the pipe you used to replace the center resonator? I'd like to have TimeValve in CT make mine but, they won't unless I send them the OE resonator and I can't drive my AMG while I'm waiting. Do you have the measurements to make the piece? Maybe they will make me the pipe with the spec's and not the actual O.E. piece. Maybe you could put me in contact with the shop that did yours.

Do you have any other performance tricks for our car. I've lowered mine with H&R's, a great improvement, but I still think that thicker sway bars would be a good addition and poly urethene bushings if I could find find them. Do you have any leads?

Any way, good luck with your C43 and I look forward to truly tweaking mine! I'd love to share sources and insight.

[william rogers]

I removed the center resinator and replace it with two straight pipes on my 86 Euro 500 SE as resinator was rusting through. Seat of the pants feel it seems to have more power in the upper RPM range, as the car is geared very high it's hard for me to feel any difference in stoplight acceleration........
William Rogers......

[-fad]

I share Manny and blackmercedes opinion based upon my experience with old school carb'd motors (larger diameter exhaust reduced initial backpressure and provided more noise but yielded lower low-end performance/torque)

Perhaps trans or driveline is slipping? Other things to take a look at: accel linkage/ potentometer, bowden, trans/ trans modulator, leak down and compression test

Do you have before and after dyno with/ without the new exhaust? Any software upgrades in the works?

Let us know what it turns out to be
-fad